Laser protection cabins are used to screen off working spaces in which laser processing machines are operated. Such screening from the working space environment is stipulated in particular for reasons of safety at work. In accordance with the relevant safety regulations, it is necessary to guarantee that, including in connection with irregular operating states of the laser processing machine and at least for a limited period of time, no harmful laser radiation can be emitted from the interior of the working space into the working space environment.
EP 1 908 546 A1 describes a working space, with a laser processing machine in the interior of the working space, which is screened off from the working space environment by means of a laser protection cabin. On its side facing the laser processing machine, the laser protection cabin has a laser beam reflector by means of which the predominant part of the laser radiation that is emitted by the laser processing machine and strikes the laser beam reflector is reflected diffusely. A diffusely reflecting metal surface, in particular an aluminum surface, can, for example be used as a laser beam reflector, and can, for example, be provided with irregularly profiled surface structures in order to bring about intensive scatter of the laser light. Aluminum is particularly suited as a material for the laser beam reflector on account of its low weight and relatively low thermal conductivity.
U.S. Pat. No. 4,650,287 A discloses a laser-light shield with a metallic substrate with a radiation-absorbing coating in the form of a flame-sprayed film consisting of ceramic metal oxide. A surface of the metallic substrate has unevenness, the height of which is greater than the thickness of the metal oxide film so that the upper side of the metal oxide film essentially reproduces the unevenness of the metallic substrate. The ceramic metal oxide film can, for example, consist of a combination of Al2O3 and TiO2 and is described in U.S. Pat. No. 4,650,287 A as being extraordinarily heat-resistant and absorbent.
U.S. Pat. No. 5,309,925 describes a reflective metallic foil on which, to protect people against laser radiation, a surface structure is applied which diffusely reflects a laser beam that strikes the foil, scattering the laser beam in multiple directions.
DE 20 2006 006 823 U1 describes a non-flammable textile material on which, on at least one side, a foil material layer is applied that, on its externally facing side, has at least one metal or oxide ceramic coating, applied by means of a thermal coating process, and is designed to scatter the laser beam striking it very efficiently by launching and subsequently diffusely scattering it. The foil material layer can consist of a highly reflective metal, for example aluminum, and the process-related parameters for the thermal coating can be selected in such a way that the absorption and resistance of the material are increased.
To increase the absorption of laser radiation, the prior art, for example DE 19736042 A1, also describes blackening the inner surface of a beam dump.
In the laser protection cabin described in EP 1 908 546 A1, the working space environment is protected against the laser radiation from the laser processing machine. If there are several working areas in the working space of the laser protection cabin, laser processing can take place in a first working area while, in a second working area, a person can be in the working space, for example to carry out activities at the second working area such as final inspection of the laser processing or a loading or removal process. If different working areas share equipment, for example a laser processing machine head, the working areas usually cannot simply be separated from each other with full light-proofing so that laser radiation is able to pass from one working area to another unintentionally.
In such a laser processing system, as offered by TRUMPF Inc., for example, in the TruLaser® Cell 7000 series, it is necessary to ensure that the stipulated radiation thresholds are also complied with for the radiation accessible in a working area in the interior of the laser protection cabin in which no laser processing takes place.